Aircraft that use water for runways and taxiways are well known. Some of these are originally designed as “flying boats” in which the fuselage is also a water hull. Some of these have retractable wheeled landing gear. Other aircraft have been designed or retrofitted with two pontoons for water operation. Air/water craft normally use the air propulsion engine for propulsion on water, and the air rudder for steering on water.
Some air/water craft have been designed for operation as sailcraft, using a wing as a sail. For example U.S. Pat. No. 5,181,674 (Apgar) shows an air/water craft with wings that pivot individually or in unison about an axis parallel to the longitudinal axis of the fuselage. A wing can be rotated to a generally vertical orientation to act as a sail. This craft has twin pontoons that pivot about a vertical axis to set a course for the sailcraft while orienting the sail wing as needed for propulsion in a given wind direction.